THE PITUITARY GLAND OF THE AFRICAN LUNGFISH, PROTOPTERUS AETHIOPICUS

¹ From the Biological Laboratories, Harvard University, Cambridge, Mass.

This study is based on two male specimens, 14 inches long. The flattened pituitary gland lies close to the brain and is located caudally to the infundibulum. There is no sella turcica in the cranial floor.

In a ventral view of the brain only the infundibular process and the flattened ovoid pars anterior are visible. The infundibular process is wide and thin-walled except in a median ventro-caudal region applied to the pars intermedia, where a considerable thickening occurs. The epithelial portion of the gland possesses a conspicuous hypophysial cavity which almost completely separates an antero-dorsal intermediate zone from a more elongated ventro-caudal pars distalis. The pars intermedia is composed of open or losed epithelial diverticula which are associated with the hypophysial cavity and are interdigitated with the compact fibrous portion of the infundibular process. The pars distalis is composed of cords of epithelial cells.

The majority of the intermedia cells are basophilic but a number of cells reacting with orange G are present, especially in the region immediately in contact with the neural tissue. In the pars distalis chromophobes are rarely seen. After Heidenhain's azan method three types of chromophilic cells may be distinguished, deeply staining basophiles, acidophiles selectively stained with orange G and acidophiles reacting with azocarmine.

There is no pars tuberalis or saccus vasculosus.